Purpose: To investigate the structural validity, internal consistency, measurement invariance, and construct validity of the Dutch PROMIS-29 v2.1 profile, including seven physical (e.g., pain, physical function), mental (e.g., depression, anxiety), and social (e.g., role functioning) domains of health, in a Dutch general population sample including subsamples with and without chronic diseases.
Methods: The PROMIS-29 was completed by 63,602 participants from the Lifelines cohort study. Structural validity of the PROMIS-29, including unidimensionality of each domain and the physical and mental health summary scores, was evaluated using factor analyses (criteria: CFI ≥ 0.95, TLI ≥ 0.95, RMSEA ≤ 0.06, SRMR ≤ 0.08). Internal consistency, measurement invariance (no differential item functioning (DIF) for age, gender, administration mode, educational level, ethnicity, chronic diseases), and construct validity (hypotheses on known-groups validity and correlations between domains) were assessed per domain.
Results: The factor structure of the seven domains was supported (CFI = 0.994, TLI = 0.993, RMSEA = 0.046, SRMR = 0.031) as was unidimensionality of each domain, both in the entire sample and the subsamples. Model fit of the physical and mental health summary scores reached the criteria, and scoring coefficients were obtained. Cronbach's alpha for the seven PROMIS-29 domains ranged from 0.75 to 0.96 in the complete sample. No DIF was detected. Of the predefined hypotheses, 78% could be confirmed.
Conclusion: Sufficient structural validity, internal consistency and measurement invariance were found, both in the entire sample and in subsamples with and without chronic diseases. Requirements for sufficient evidence for construct validity were (almost) met for most subscales. Future studies should investigate test-retest reliability, measurement error, and responsiveness of the PROMIS-29.
Keywords: Mental health; PROMIS; Patient-reported outcomes; Physical health; Psychometric properties; Validation.